1. Field of the Invention
This invention relates to a measuring device for determining the distribution rate of agricultural chemicals, seeds and other materials applied upon the ground.
2. Description of the Prior Art
There are a wide variety of agricultural materials in use today which are distributed on the land by a dispensing machine. These materials may consist of solid matter such as seeds, granular fertilizers or other chemicals, or may comprise a sprayable liquid herbicide, fertilizer or other plant or soil treatment. These substances may be applied upon a soil surface, plant surface, or within the soil by means of a soil opener mechanism. Generally, such substances are distributed by a material-dispensing machine having a plurality of outlets arranged in a row across the width of the machine, and as the machine forwardly travels a certain lineal distance, the row of outlets applies the substances over an area of land.
The rate at which material is dispensed is often very critical for successful farming practice. For example, inadequate application of seeds, insecticides or herbicides will usually result in unsatisfactory crop yields; unfortunately, the problem is often not noticed until the damage is beyond repair. Alternatively, overapplication of these costly materials can have a severe adverse effect on farm profits. In either case, time and fuel are also wasted. As a consequence, there is a great need for accurately checking the output of substances from these dispensing machines.
Machines for seeding, fertilizing, and applying chemicals each have a particular type of rate dispensing mechanism which is adjustable to vary the amount of materials applied as the machine traverses the ground. Often, such machines have a delivery-restricting aperture which may be variable in size to produce the desired rate of flow. The size adjustment mechanism on the machine usually must be set according to an instruction manual containing information concerning an approximate setting for the aperture depending on the type of material being dispensed. However, reliance on such a setting will cause inaccurate results, due to mechanical wear in the aperture and clogging of the delivery tube.
When sowing seeds, such aperture-dependent dispensing machines may cause improper plant populations due to differing grain sizes or shapes. For example, different batches of wheat may lead to dissimilar plant populations because one batch may have smaller, heavier seeds while the other batch has larger, lighter seeds. Again, because the dispensing mechanism meters the seeds on the ground by size or volume and not by mass, the farmer's dependency on the aperture setting can result in costly error.
Furthermore, although the dispensing machine normally meters the materials onto the ground according to their size or volume, the proper application rate of these substances is often specified in terms of a given weight of materials applied to a certain area of land. For example, while a granular soil insecticide may be metered out of a dispensing machine by an aperture or other size-dependent mechanism, the application rate of the insecticide is often specified by the manufacturer in terms of a kilogram per hectare quantity. To adjust the dispensing rate, the farmer would refer to an instruction manual to determine the proper setting of the size-variable aperture, and then must compensate for the density of the material if the latter is hygroscopic. Even though time consuming, these computations still can give at best only a rough estimate of the weight of the material actually applied to the ground.
Various methods have been used in the past to check the actual dispensing rate of these machines. Commonly, the machine is filled with the materials and then driven over a known area. By measuring the amount of materials used to then refill the machine, the farmer can determine the application rate by dividing this amount by the area of land covered by the applied materials. Unfortunately, this method is subject to numerous shortcomings. The farmer must make difficult and time consuming calculations, and must compensate for any settling of the material in the hopper of the machine as the latter is driven over the rough ground. Also, if the amount was measured by volume, the farmer must multiply by an assumed density to obtain the weight distributed per area, consequently introducing further potential for error.
Another method in use which measures the volume output of materials from a dispenser comprises a small calibration bag or cylinder placed under one of the nozzles or delivery tubes of the dispensing machine. In use, the farmer first determines the nozzle or delivery tube spacing on the machine and then forwardly drives the machine a certain lineal distance that will cause the materials to be distributed over a certain quantity of land area. After the sample is collected in the bag or cylinder, calibration marks on the bag indicate the volume of material that would normally be dispensed over an acre or hectare. For example, if the nozzle spacing on the machine is 10 centimeters, the farmer would put the bag under the nozzle and move the machine 100 meters, and thus the sample collected in the bag would represent the amount of material normally applied to one ten thousandth of a hectare. Next, the farmer would locate a calibration mark on the bag corresponding to the level of materials in the latter and read an adjacent numeral representing the liters of materials distributed over hectare. Thus, although the farmer has actually collected the sample over only one ten thousandth of a hectare, the farmer can directly read a value on the bag expressed in terms of liters per hectare.
Unfortunately, such calibration bags or cylinders also utilize a volume measurement which is subject to the same shortcomings described hereinabove. Because the material is measured by volume, readings for solid substances can be affected by settling or packing as the machine travels over the rough surface of the field. Also, most materials are sold or measured by weight and the volume per area measurement given by these bags must often be then converted to terms of weight per area, thus leading to additional complications in use and also introducing a possibile computation error. As a result, these calibration bags and cylinders have not satisfactorily met the needs of most farmers.
Some machines have electronic monitoring means to count population or to measure the volume or mass being dispensed. However, these systems are dependent on the accuracy and consistency of the dispensing mechanism. Also, the electronic monitors which depend on volume displacements cannot compensate for various densities.